* problem*: Find the set of all values of such that can take all real values.

* solution*:

Now takes all real values if discriminant is allways .

So now we have to find the all values of such that for all |R.

…(i)

Now this is a equation of upside open parabola. If the discriminant is of equation (i) then will always positive.

*Conclusion*: If , then can take all the values as varies over |R.